A carombilliards metaphor, it refers to an object ball positioned and being approached in such a manner that a near miss will rebound off a cushion and still score. It is as if the ball were larger than normal, making it easier to contact. Normally a ball a couple inches from a rail is a big ball, but only if being approached from an angle and if all the prerequisite rails have already been contacted. A ball near a corner can effectively be a foot wide. Not to be confused with the eight-ball term "the big balls". In older British usage the concept was referred to as "large ball". See also "big pocket".